AnimatableKeyframe

Can be either null, string, number or an object of the form:

value?: string | number

The value of the keyframe.

after?: string | number

An ending value for the keyframe, useful when animating non-interpolatable values. Will be applied at the very end of the keyframe, keeping the value until then.

offset?: number

At what time in the animation to play this keyframe, defined in seconds. By default, if no offset is specified, all keyframes are equally far spaced apart.